Appium with SeleniumGrid (testNG) : org.openqa.selenium.SessionNotCreatedException: A new session could not be created. (Original error: The following desired capabilities are required, but were not provided: deviceName)

Following is the java file:
####Imports and class level declarations*******

//To fetch network details
public static String networkConnection=””;

@BeforeSuite//The annotated method will be run before all tests in this suite have run.
@Parameters({“device_id”})
public static WebDriver atStart(@Optional (“Abc”) String device_id) throws InterruptedException, IOException
{
//setup property with webdriver to create/cutomize a session with webdriver
DesiredCapabilities capabilities = new DesiredCapabilities();
System.out.println(“”+device_id);
if (“36C35E3F00B8B341″.equals(device_id))
{

It is throwing the error as follows:
org.openqa.selenium.SessionNotCreatedException: A new session could not be created. (Original error: The following desired capabilities are required, but were not provided: deviceName) (WARNING: The server did not provide any stacktrace information)

Could you please tell me whats going wrong?
I have already mentioned the capabilities that have been suggested.